This invention relates to an improved coupler for releasably connecting a prosthetic device such as an artificial leg or arm to a sleeve which receives the stump of an amputee""s limb and has a projecting locking stud, for example, as disclosed in U.S. Pat. No. 5,376,129. As illustrated in FIGS. 9-11 of this patent, it is known to have an attachment device or coupler which uses a retractable release stem having a wedge-shaped inner end portion or pawl for engaging one of a plurality of grooves formed within the locking stud projecting from the sleeve. This general form of attachment device or coupler is made by the inventor of the present invention and sold by Prosthetic Design, Inc. of Clayton, Ohio under the trademark PDI. This company also sells another coupler manufactured by the inventor of the present invention and wherein the pawl is connected by a pivotal lever to the release stem so that the pawl is retracted to a released position when the stem is pushed inwardly. It is also known to retain the sleeve within the socket by means of a suction coupler, for example, of the type shown in U.S. Pat. No. 5,662,715 and U.S. Pat. No. 5,702,489 which disclose couplers made by the inventor of the present invention for the Assignee of the patents.
It has been found desirable to provide a prosthetic attachment device or coupler which provides the amputee user with a means for locking the coupler so that it may not be accidentally released, for example, by accidentally pushing or pulling the actuator stem. It has also been found desirable to provide a coupler which may be easily converted and assembled to provide an actuator stem which may be pushed to release and/or pulled to release and/or rotated to release the locking stud from the coupler. In addition, the coupler should provide for conveniently receiving the locking stud projecting from the sleeve, and for a positive and dependable lock with the locking stud.
The present invention is directed to an improved coupler for releasably connecting a prosthetic device such as an artificial leg to a sleeve configured to receive the stump of an amputee""s limb and which provides all of the desirable advantages mentioned above. In accordance with a preferred embodiment of the invention, the sleeve has a projecting locking stud with a series of axially spaced circumferential grooves. The attachment device or coupler includes a generally cylindrical body having an upper section and a lower section each formed or molded of metal or a rigid plastics material. The lower section is secured to the bottom wall of the socket by a set of four screws having hex recesses in both ends, and another set of screws secure the upper and lower body sections together.
The top surface of the upper section has a generally conical surface interrupted by a circumferentially spaced guide grooves which converge downwardly for guiding the end of the locking stud into a tubular bushing confined between the body sections. The bushing retains a series of peripherally spaced balls which are retained in the bushing by a surrounding tubular fitting which also provides for axial movement of the tubular bushing for shifting the balls between locking positions engaging one of the grooves in the locking stud and retracted released positions. Axial movement of the bushing is produced by rotation of a pair of actuating pins spaced to engage opposite sides of the bushing.
The actuating pins have cross pins which are spring biased against cam surfaces and locking surfaces on an actuator stem extending radially outwardly from the coupler through a clearance hole within the socket. The actuator stem is provided with various cam surfaces and locking surfaces which provide for locking the stem against axial movement and cam surfaces which provide for either push to release and/or pull to release and/or rotation to release in addition to rotation to a locking position. The actuator stem also has an outer gripping knob with a cross slot and provides the user with both a non-visual and a visual indication of each position of the actuator stem. A flexible guide stem projects from the locking stud to assist attachment of the sleeve to the socket and coupler.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.